UCSB WMRS Cosmology

Our group has several ambitious goals for the WMRS
Barcroft station: Acquisition of CMBR (Cosmic Microwave Background Radiation)
anisotropy data from the BEAST telescope; installation and operation
of a sensitive CMBR Polarization experiment in the Barcroft dome; planning
for and securing funding for a larger, more aggressive CMBR polarization
telescope (the Densely Instrumented MMIC Correlation Array Module or
‘DIMCAM’). In addition, we are doing extensive work preparing the site
for these instruments in terms of infrastructure (communications, power
handling (UPS, surge protection, power distribution), 24/7/365 automated
weather monitoring, and physical facilities). We made major progress in all these areas during 2001.

Science

CMBR
anisotropy and CMBR polarization anisotropy are probes of processes
and structure in the early universe. CMBR Anisotropy measurements constrain the processes by which
structure could have formed, the nature and distribution of matter in
the universe, and the small number of cosmological parameters which
describe the universe as a whole, including the Hubble constant, the
cosmological constant and the average density of the universe. CMBR
anisotropies may be polarized by several processes: measuring the polarized
component of CMBR anisotropies should allow us to separate out otherwise
degenerate models, as well as distinguish the characteristic imprint
of primordial gravitational waves on the structure of the early universe.

BEAST

Starting in late 2000 and early in 2001 (January),
we brought the main components of the BEAST (Background Emission Anisotropy
Scanning Telescope) to Barcroft. Through the winter season and into
the early summer we made many trips to Barcroft so that by July, the
following were accomplished:

View of the BEAST garage during observations, 2-15-02

Garage: We modified one of two available Barcroft garage
structures by cutting a portion of the roof, raising it and mounting
it on rails to allow it to roll open. This allows the telescope to view
the sky without being moved out of the building. The roof is actuated
with an industrial garage door opener, and has been working in all seasons
at Barcroft (including during a trip in February 2002). Much of the
success of this work rested on the ingenuity, skill and hard work of
WMRS staff (Rick Masters and Dave Trydahl).

Power Handling: One
of the challenges of working at Barcroft turned out to be power line
problems. We lost several computers and some data acquisition equipment
to power line surges before we acquired and installed appropriate power
conditioning hardware, including ferro-resonant transformers and high
capacity UPSs (Uninterruptible Power System). We have had no problems since installing these systems. In addition to this we contracted an electrician/carpenter to
install new breaker panels and appropriately sized circuits in both
garages and the dome.

Telescope: The BEAST
telescope was originally designed to make measurements from a high altitude
balloon, for periods of up to 10 days. We made extensive modifications
to the system to allow extended observations from the ground and assembled
the telescope at Barcroft in the garage. By late July we had the system operational, with full time data
taking commencing in early August. To date we have around 200 Gbytes
of Cosmology data from Barcroft and we are in the process of analyzing
it.

Map made from Two days of beast data. Top panel shows full map (the measured area is about 3000 square degrees,
the center of the panel is the north celestial pole).Extra noise in
the upper left quadrant is from data missing due to bad weather. Bottom panel is a closeup of this map showing some point sources, the Cygnus
A radio galaxy is at the center of the panel.

Weather and site monitoring: During the summer we installed a weather station, downloading weather
data by hand during normal operations of the telescope. During our recent
trip to Barcroft (Feb, 2002) we set the system up to automatically send
data to UCSB via the STARBAND satellite internet link. At the same time
we installed a webcam for visual record of the site conditions when
personnel cannot be there. (http://moseisley.deepspace.ucsb.edu ). In addition to this we were able to borrow a standard NRAO ‘tipper’,
an automated instrument for measuring atmospheric opacity. This standardized
instrument allows direct comparisons among millimeterwave/infrared observing
sites. We operated the tipper
from early September thru late October. We were fortunate to have the
tipper loaned to us by A. Beasley of the OVRO, and we hope to borrow
that one or another one for longer term measurements of the site. For the time period measured, Barcroft was comparable to
Mauna Kea, considered one of the best IR observing sites in the world.

Barcroft Dome

Dome
Refurbishment: We have been working to upgrade the dome facility
in preparation for bringing the first generation polarimeter telescope
to Barcroft. This includes upgrading the power systems as describe for
the BEAST garage, strengthening the telescope support pedestal, replacing
weatherstripping, insulating the instrument room, and upgrading the
dome control system to allow computer control of the door and azimuth. This work will be completed in the early part
of the Summer, 2002 , in time to install the telescope.

Polarimeter: The instrument being readied for the dome consists of three (3) receivers:
one ‘delta T’ at 90 GHz, one polarimeter at 40 GHz, and one polarimeter
at 90 GHz. The receivers are
cooled to 20 Kelvin with a mechanical cooler and coupled to a second
copy of the BEAST telescope optics. This instrument will be dedicated to making a small but very
sensitive map of CMBR polarization fluctuations near the North Celestial
Pole. The receivers are ready and being integrated to their electronics,
while the telescope sytem is being integrated separately. All elements
should be tested together in Santa Barbara by mid May, ready for Barcroft
sometime in June.

“Lab Garage”

We
made major progress towards making Barcroft usable by our students by
having one of the ‘garages’ refurbished into a comfortable laboratory.
This provides a controlled comfortable environment for the students,
most of the computers and test equipment, even in the harshest conditions
at Barcroft in February. WMRS staff also helped significantly in setting
up this lab.

DIMCAM

DIMCAM
is our name for a large format array of correlation Polarimeters, specially
designed detectors for measuring CMBR polarization. We submitted two
major proposals the the National Science Foundation to support this
specific project development, decisions will be made later this year.
In the meantime, design work and planning continues, assuming a good
outcome for the proposal.

Communications

Reliable
communications with reasonable bandwidth are critical to the success
of our program, from simple interactions debugging instruments over
the phone, downloading test data during observations, remote monitoring
of the site for weather and atmospheric conditions, all the way to potential
remote operation of the telescope via the web. Three systems brought
up to Barcroft are making a huge difference
to how we can work there:

We
have a base station style cell phone giving us reliable phone and
fax contact from the instruments to Santa Barbara. This allows us
a network of phones from the dome to the two garages and the Pace
lab.

The
Starband satellite internet link originally set up by WMRS is now quite reliable (and is running
the webcam and weather data downlinks). This has be valuable for sending
data back and forth from UCSB to Barcroft.

The
T1 RF internet system implemented by WMRS (J. Szewczak) is coming online and will provide the bandwidth and reliability
to serve diagnostic webcams and perhaps allow remote operation of
the telescopes.

Funding

Our
efforts at Barcroft have been funded from a variety of sources, all
of which have been very important to our success to date. In addition
we have applied for significant funds from NSF to support future work. We have made a summary of the totals in the other part of this report,
here we outline how the different sources contribute.

NASA Balloon program

Our NASA funds have been the
primary support up to the start of our work at White Mountain. We developed
and flew the BEAST telescope on NASA grants. The spare optics and much of the instrument infrastructure for
the polarimter depend heavily on our previous work on the NASA payload.
Without all this investment there would be no telescopes to site at
Barcroft.

NASA/ESA Planck Surveyor

Planck
is a second generation CMBR space mission we are involved in. While
NO Planck funds have been spent on WMRS work, there has been very significant
technology transfer. The receivers being used for the polarimeter were
developed with JPL collaborators (T. Gaier, M. Seiffert) based very
directly on the Planck receivers, and using the same devices from TRW.
These are state of the art receivers with state of the art devices and
performance, and could only be available to our program through our
extensive collaboration with JPL on the Planck and BEAST programs.

NSF Extragalactic- COMPASS

Compass
is a joint venture with the University of Wisconsin, Madison and the
University of Miami. It has
been funded by NSF extragalactic astronomy for several years, looking
for polarization anisotropy in the CMBR from a site in Wisconsin. The
collaboration plans to move the operation and future instruments to
Barcroft due to the superior observing conditions. The 3 element polarimeter
described above is part of this collaboration.

NSF Extragalactic,NSF MRI-DIMCAM

These
two proposals to the NSF include our COMPASS collaborators and detail
the large format polarimter array we plan to install at Barcroft.

Brazilian Cosmology Center

We
have an active collaboration with researchers at INPE (the Brazilian
Space Agency). For the past
year they have been providing significant amounts of support in the
form of hardware contributions, totaling $100,000. These contributions range from very sensitive angle resolvers
to state of the art custom electroformed microwave feedhorns.

WMRS Support

All
of the work described above could not have been accomplished without
the enthusiastic support of the WMRS staff and management. Both Dave
Trydahl and Mike Morrison (outgoing and new managers respectively) made
sure we had what we needed to accomplish our work. Rick Masters has
been tremendously helpful with advice, winter transport and logistical
support as well as his work on the buildings. J. Szewczak’s
work on the internet link has been much appreciated, and we look forward
to taking full advantage of it. In
addition all the OVL and Barcroft summer staff were enthusiastic and
helpful, with normal logistics and helping hands for the students and
staff. We’re all looking forward
to a long and productive collaboration.

WMRC Crooked Creek and Barcroft Stations are operated under special use permit with the Inyo National Forest.